• Resources Recycling
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• v.21 no.6
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• pp.12-22
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• 2012

This study investigated a utilization technology of light burned dolomite. light burned dolomite ($CaMg(CO_3)_2$) generated in furnace (steel manufacturer) is an alternative to quick lime. Using light burned dolomite has an effect on reducing the consumption of fluorite slag MgO concentration in supersaturated solution by prolonging the life of softening effect. Armophous MgO, not containing periclase is formed by firing dolomite under $800^{\circ}C$. It has larger surface area and higher reactivity than periclase, and also shows better expansion effect than quicklime. Due to those effects, therefore, armophous MgO produced from light burned dolomite is used as an alternative expansion agent in mortar. In the experiment, characteristics of light burned dolomite were compared to those of existing expansion agents such as anhydrite and quicklime. Then, each expansion and shrinkage rates were measured over a period of about 3 months in both of 1m Jis mold at labscale and apartment mortar flooring at field scale. In the result, it was observed that light burned dolomite in mortar flooring more compensates for the expansion and shrinkage rates than the existing expansion agents, showing low expansion rate of below 0.05% and also decreases the crack.

• Korean Journal of Weed Science
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• v.8 no.1
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• pp.15-22
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• 1988

In this experiment, interactions between light and other factors such as chilling, alternating temperature, moisture, content, oxygen, and seed coat which affect germination of Oenothera lamarckiana Ser. seed were investigated to study the physiological effects of light on the germination. Light induced the initial stage of seed germination before radical protrusion by affecting embryo rather than seed coat even under anaerobic condition or low water potential (-18 bars). This light effect on germinability of seed was suppressed by blue light irradiation and the effect was increased with increment of blue light intensity and irradiation time. However, the blue light effect was reversible. Chilling, alternating temperature, softening of seed coat and light showed promotive interaction in the induction of seed germination. Irradiation of filtered light (monochrome), however, reduced chilling effect on germination. Hydrogen-ion concentration and gibberellic acid treatment had no effect on light or dark germination.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.765-770
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• 2017

GTD111 DS of nickel base superalloy has been used for gas turbine blades. In this study, low cycle fatigue test was conducted on the GTD111 DS alloy by setting conditions similar to the real operating environment. The low cycle fatigue tests were conducted at room temperature, $760^{\circ}C$, $870^{\circ}C$, and various strain amplitudes. Test results showed that fatigue life decreased with increasing total strain amplitude. Cyclic hardening response was observed at room temperature and $760^{\circ}C$; however, tests conducted at $870^{\circ}C$ showed cyclic softening response. Stress relaxation was observed at $870^{\circ}C$ because creep effects occurred from holding time. A relationship between fatigue life and total strain range was obtained from the Coffin-Manson method. The fratography using a SEM was carried out at the crack initiation and propagation regions.

• Korean Journal of Food Science and Technology
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• v.38 no.1
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• pp.35-41
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• 2006

Possible application of hurdle technology extention of shelf-life of fresh-cut apples was investigated by evaluating various hurdle factors known to be effective microbial growth inhibitors and their synergistic effects. Fresh-cut apples treated with chitooligosaccharide or grapefruit seed extract (GSE) showed higher microbial counts than those treated with distilled water during latter half of storage period, and at high concentrations. Citric and malic acids showed similar results, although microbial counts of fresh-cut apples treated with 0.75% or higher concentration of citric acid increased at 4 days of storage at $18^{\circ}C$, indicating malic acid is more effective than all hurdles tested for controlling microbial growth. Using ascorbic acid and calcium chloride as additional hurdles to control browning and softening, minimum and maximum compositions of dipping solution were: 0.25 : 0.5 : 0.25% and 0.75 : 1.0 : 0.75% malic acid: ascorbic acid: calcium chloride, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.772-781
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• 2020

A direct shear member resists external forces through the shear transfer of reinforcing bars placed at the concrete interface. The current concrete structural design code uses empirical formulas based on the shear friction analogy, which is applied to the horizontal shear of concrete composite beams. However, in the case of a member with a large amount of reinforcing bars, the shear strength obtained through the empirical formula is lower than the measured value. In this paper, the limit state of newly constructed composite beams on an existing concrete girder is defined using stress field theory, and material constitutive laws are applied to gain horizontal shear strength while considering the tension-stiffening and softening effects of concrete struts. A simplified method of calculating the shear strength is proposed, which was validated by comparing it with the related design code provisions. As a result, it was confirmed that the method generally shows a similar tendency to the experimental results when the shear reinforcing bar yields, unlike the regulations of the design code, where differences in the predicted value of shear strength occur according to the shear reinforcement ratio.

• Nuclear Engineering and Technology
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• v.8 no.4
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• pp.231-242
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• 1976

The effects of temperature and pressure of leaching water on the leaching of radionuclides from bitumen-waste products were studied. The principal results are as follows: The fraction of $^{90}$ Sr and $^{137}$ Cs leached for periods of up to 120 days at 8atm was 2.1$\times$10$^{-6}$ ($\textrm{cm}^2$/g)$^{-1}$ , day$^{-1}$ and 6.02$\times$10$^{-5}$ ($\textrm{cm}^2$/g)$^{-1}$ day$^{-1}$ respectively and at 5$^{\circ}C$, 1.7$\times$10$^{-5}$ ($\textrm{cm}^2$/g)$^{-1}$ day$^{-1}$ and 4.01$\times$10$^{-5}$ ($\textrm{cm}^2$/g)$^{-1}$ day$^{-1}$ respectively. These values were lower than those in atmospheric pressure and room temperature. No diffence in the leaching rate with sea and distilled water was observed for the bitumen-waste products containing 40wt% salts. It appears that these results could be saved by improving safety in the dumping of sea. The effect of the softening point of pure asphalt or bitumen-waste product by $^{60}$ Co irradiation was increased with increasing total dose. Irradiation of asphalts at a total dose of 5.8$\times$10$^{8}$ rad showed no evidence of volume and caused no swelling. The functional groups of blown asphalt by infrared spectra are also identified.

• Food Science and Preservation
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• v.31 no.3
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• pp.433-443
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• 2024

This study investigated the effect of packaging method and root trimming on quality of green onions during storage. Two packaging methods (tied with string, S or packaged with film bag, FP) and two root trimming states (attaching the roots without trimming, AR or cutting the roots leaving about 5 mm, CR) were treated after harvest. Then, the green onions stored at 20℃ for 8 days and 1℃ for 6 weeks to investigate changes in quality. When stored at 20℃, the differences in marketability between S and FP were minimal, while when stored at 1℃, the marketability of the FP remained higher than that of S. The leaf color change in CR progressed faster than in the AR treatment group, leading to faster quality deterioration. The occurrence of weight loss, browning, and softening of stems progressed as the storage period elapsed. However, except weight loss, they were at a level that did not affect marketability within the marketability limit period determined by color change and wiltig of leaves. The allicin and quercetin contents of stems increased in the early stages when quality deteriorated after harvest but decreased as quality deterioration became more severe.

• Food Science and Preservation
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• v.12 no.6
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• pp.522-528
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• 2005

Effects of packaging and storage temperature on the quality and shelf life of mungbean sprouts(vigna radiata (L.) Wilczek) were studied Mungbean sprouts were packaged in polypropylene films(PP) and oriented polypropylene films(OPP) with 200 g, 250 g, and 300 g and stored at $4^{\circ}C,\;8^{\circ}C$ and $12^{\circ}C$, respectively. The deterioration of quality of mungbean sprouts during storage was caused by wilting of hypocotyl, abscission of cotyledon and softening of tissue. Total weight loss never exceeded $1\%$ and no visible signs of shrivelling of mungbean sprouts were observed. At $4^{\circ}C,\;30{\mu}m$ of OPP film per 250 g mungbean sprouts provided the optimal atmosphere composition(i.e. $3\%\;\O_2\;and\;5\%\;CO_2$). A shelf life of 6 days was achieved with these conditions. Hardness of hypocotyl, when deterioration in freshness began, was about 1,027.2 g when considerably deteriorated Hunter b value was 13 in deteriorated hypocotyl, vs. 11 for hypocotyl of fresh mungbean sprouts was accelerated by fluctuating storage temperature by the increment of storage time. It also was found that the optimum shelf life period was estimated to be 6, 2 and 2 days for 4, 8 and $12^{\circ}C$, respectively.

• Food Science and Preservation
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• v.16 no.2
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• pp.166-171
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• 2009

The effects of vacuum precooling(VP) on the shelf-life of polyethylene film(PE) packaged King oyster mushrooms(Pleurotus eryngii) during storage at $-1^{\circ}C$ were investigated. VP was conducted below $0^{\circ}C$ in a $-1^{\circ}C$ cold chamber of 40 minutes, and mushrooms were stored for 30 days in batches of 1kg. The weight loss of the VP-treated mushroom was slightly lower than that of control. The $O_2$ concentrations of VP-treated mushroos, within 4 days of storage, were 2.44-14.50 %/kg-package/hr, thus higher than control values(2.01-8.19%/kg-package/hr). $CO_2$ generation of VP-treated mushrooms, again within 4 days of storage, was 0.47%/kg-package/hr, thus lower than that of controls(0.58%/kg-package/hr). The $CO_2/O_2$ ratio peaked on day 4 of storage in the control group, tbut no such peak was observed in VP-treated mushrooms. In the VP-treated fungi, lightness was higher, and redness and yellowness lower, than in controls, at all storage times.. In VP-treated mushrooms, strength, hardness and chewiness were significantly higher than in controls, but there were no significant differemces in springiness or cohesiveness. Softening and breakdown of under-cap wrinkles were observed in control mushrooms stored for 30 days, but occurred to a lesser extent in VP-treated fungi. Stipe reticulum tissue vessels in the 30 day-stored VP-treated mushrooms were relatively well-defined and clear, but were softer and diffuse in the control fungi. The results thus confirmed that VP after harvest enhanced mushroom shelf-life and PE packaging prolonged storage time. The data will have industrial applications.

• Korean Journal of Plant Resources
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• v.9 no.2
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• pp.151-155
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• 1996

For improvement germination rate of Cirsium setidens, wet seeds were storaged for 20 to 80 days at $4^{\circ}C$ and germinated at $18^{\circ}C$ in the dark or light condition. To assess the effects of shading and plant age on the growth, fresh yield and seed yield under rain shelter in highland at altitude of 800m above sea level, seeds were sown in an open field in late september,1990. In early May the next the seedlings were transplanted for vegetatable and seed production in the plastic houses for rain shelter. They were grown from 1991 to 1993 in the houses covered with the shading nets ranging from 0 to 70% for vegetable production and 0 to 50% for seed production. Germination rate inceased as the storage period lengthened, and the rate came to $60\sim80%$ at 60days after germination. It was more effective in lighting than in darkness. For vegetable production, the shading net treatments showed more values in almost the characters checked at the third year than the non-shading treatment. No. of stem, no, of leaves, stem length and degree of softening were no different between shading net treatments, but the other characters were significantly different. Ratio of survival, density of chlorophyll and ratio of dry matter of plants were highest in the plots of 50%, 70%, and 30% of shading, respectively. The highest fresh yield was recorded from 2-year plants, 70% of shading from them showed the greatest yield. The highest seed yields were produced 2-year-old plants of non-shading plot. For seed production, the non-shading treatment is best, and the highest seed yields were obtained in both the second and third years.